When adhering a collecting device to human skin the major situations that need to be considered are the following:
1) Wearing the adhesive; the adhesive should stay in place and not detach or fall off because of skin or body movements.
2) Removing the adhesive; the adhesive should be easy to remove without excessive pain or skin damage as a result.
This is a paradox—the adhesive should stay in place nicely, but should also be easy to remove. The solution today is a compromise in adhesive characteristics that accommodate both situations.
EP Patent No. 0437944 discloses a layered adhesive construction with at least three layers. One layer is a backing layer, the skin-facing layer is an adhesive and the layers in between can optionally be adhesives. The purpose of this construction is to maximise the moisture vapour transmission rate of the overall dressing and it is advantageous for use in wounds having heavy exudates as well as moisture from external sources.
EP Patent No. 0 300 620 discloses a two layered construction of cross-linked silicone where the skin facing layer is an adhesive. Only one layer has adhesive characteristics, while the other layer is elastic and thus does not contribute to the peel strength of the adhesive. In essence, the second layer of cross-linked silicone acts as a backing for the adhesive.
EP Patent No. 1527789 discloses a layered hydrocolloid adhesive wafer for ostomy. The adhesive layers in the wafer both have a considerable amount of hydrocolloid (HC) particles dispersed in them making the adhesive layers hard or giving the layers high moduli.
There has now surprisingly been found a way to isolate the two situations mentioned above, such that the ability of the adhesive to stay in place is less affected by the ease of removal.